1. Field of the Invention
This invention relates to a painting tool applicable to painting of a large-scale structure.
2. Description of Background Art
FIGS. 6 and 7 show an example of conventional painting tool. This painting tool comprises a first hood 101, covering a part of a surface to be painted (wall surface) 100 as being supported by a wall-surface working device (not depicted) movable along the surface to be painted 100; a second hood 103 disposed within the first hood 101 via a driving means 102 so as to be movable along the surface to be painted 100; a pair of painting rollers 104 disposed within the second hood 103 so as to face the surface to be painted 100 and come into contact therewith; and a spray gun 105 attached to the innermost wall of the second hood 103, so as to perform spray painting and roller painting in parallel.
FIGS. 8 to 10 show another example of conventional painting tool. This painting tool comprises a working truck 201, which is movable on a surface of a structure to be painted (wall surface) 200 by means of a wheel 201a and a magnet device (not depicted) as being remote-controlled by an operator; a plunger pump 202; a paint container 203; a chamber 204; airless spray guns 205, 205 attached to the working truck 201; a solenoid valve 206 for controlling an amount of paint emitted from each airless spray gun 205; a paint supply tube 207 extending to each airless spray gun 205; an arm 208 for linking the paint supply tubes 207 together; a pivotal axis 209 pivotally connecting a center part of the arm 208 to the working truck 201; a rotary axis 210 disposed in the working truck 201; a worm 211 attached to the rotary axis 210; a worm wheel 212, on the working truck 201 side, in mesh with the worm 211; a rod 213 linking an eccentric position of the worm wheel 212 with a member 208a on the arm 208 side; and a flexible paint supply hose 214 linking each paint supply tube 207 with the chamber 204. As the plunger pump 202 is operated, the painting tool draws in the paint contained within the paint container 203 and sends thus drawn paint to the chamber 204 by means of the pressurized air supplied from a compressor. After the amount of emission is controlled to a predetermined level at the chamber 204, the paint is successively fed to the paint supply hose 214, the paint supply tube 207, and the airless spray guns 205, 205, from which it is emitted onto the surface to be painted 200.
In the paint tool shown in FIGS. 6 and 7 and that shown in FIGS. 8 to 10, the distance between the tip portion of the spray nozzle and the surface to be painted (hereinafter referred to as spray distance) is set to a substantially constant level from the viewpoint of paintability.
When there is an obstacle such as piping on a moving path for painting, however, spray distance +.alpha. is necessary. In such a case, .alpha. becomes considerably large in the painting tool shown in FIGS. 6 and 7. In the painting tool shown in FIGS. 8 to 10, on the other hand, when the gap between the surface to be painted and an obstacle is smaller than the height of the working truck 201, the latter cannot pass through this gap, whereby its painting area may be disadvantageously narrowed.